The use of polarizer filters is known from photography applications in order to improve contrast. In photography applications, the polarizing angle needs to be adjusted in order to get a maximum suppression of the reflections, which on a photo camera is done manually. The adjustment of the polarizing angle is dependent on the position of the sun and environmental circumstances, to mention but a few such as reflections on a water, which tend to blind the observer and prevent seeing what is in the water. To improve the observation conditions in photography, the polarizers used with photographic cameras are adjusted accordingly. Since the user of the photographic camera is close to the camera, the adjustment of the polarization angle by adjusting the polarizer can be done manually and does not constitute a problem.
For video systems used as CCTV systems, there exists the problem that for video systems using a sensor (either CCD or CMOS)-camera, in the following referred to as CCTV applications, the sensor-camera is mounted in places that in general are not nearby or not easy to access. Since the user of a sensor-camera, i.e. the user of a CCTV application, is not near to the sensor-camera, the change of a polarization angle cannot be realized manually. However, the polarizing angle needs to be adjusted in order to get the maximum suppression of the reflections. In order to realize an adjustment of the polarizing angle, a motor is used. Video cameras used as CCTV-cameras in general have a video detector to establish a measure for the video level. Many forms of detectors are known, some just averaging the video contents over a frame time, or summing all pixel values in a frame which is a representation of the video, or detecting the peak value in a frame of the video. Here, the form of the video detector is of less importance. The assumption made is that the output of the video detector is a representation of the video level.
Further, there exists the requirement to maintain a sensor-camera's sensitivity under minimum light conditions to realize a use of the CCTV application even during night times.